This invention relates to a crane mechanism and more particularly to a crane mechanism having a swing arm which can be readily controlled by an operator to position the swing arm at desired positions.
Whereas heretofore various known crane devices operated to carry a load along generally circular or arcuate paths due to the pivotal mounting of the crane boom or swing arm, the mechanism of the present invention is operable to provide substantially straight horizontal or vertical movements of the load carried by the crane so that the crane operator can readily predict the path of travel of the load.
The principles of the present invention may be incorporated into cranes, servo arms, excavating machinery or other similar types of devices. By way of example, when incorporated into a servo arm, the latter may be used in industry and operated by one man to lift and move heavy parts which are being machined, pressed, assembled or otherwise worked on, the operation of the servo arm being such that the single operator can effect lifting and moving of such items along controlled and readily predictable paths of travel.
The principles of the present invention may be incorporated in a crane mechanism, utilizing a pantograph link mechanism in connection with a derrick crane or the like and having a crane boom, a swing arm pivotally connected to an end of the crane boom, and two associated arms which are so disposed as to form a pantograph or parallelogramic link mechanism. The associated arms are disposed parallel to the boom and swing arm respectively and are pivotally connected mutually at the parts of their intersection, so that displacement of the connecting part of the associated arms will cause a larger corresponding displacement of the lower end of the swing arm.
The crane boom consists of two parallel boom arms of equal length while the swing arm consists of two parallel arms of equal length. The pair of boom arms and the pair of swing arms are pivotally connected to a connecting member. The lower end of the two swing arms are pivotally connected to a swing means, whereby a line connecting the pivotal connection of the two swing arms to the connecting member is parallel to and equal in length to a line connecting the pivotal connection of the swing arms to the swing means, and the aforementioned lines are maintained at a horizontal disposition or at a certain angle at all times.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.